1. Field of the Invention
This invention is in the field of sheet forming devices.
2. Description of the Prior Art
A representative sample of the prior art is disclosed in the following U.S. patents:
U.s. pat. No. 2,238,534 issued to A. McDonald; PA1 U.s. pat. No. 2,989,780 issued to S. S. Zimmerman; PA1 U.s. pat. No. 3,179,726 issued to W. M. Perry; PA1 U.s. pat. No. 3,273,203 issued to F. A. Ross; and PA1 U.s. pat. No. 3,640,666 issued to B. T. Jope et al.
None of the prior art device provide a high production capability which may be achieved by immediately forming a plastic sheet which moves onto the forming device immediately from the extruder. By allowing immediate formation of the desired configuration of the sheet as the sheet passes from the extruder, intermediate steps are eliminated with the result that a continuous in line forming is achieved. Traditional forming dies are expensive to produce and to maintain. The invention disclosed herein provides for the formation of the sheet through the use of vacuum pressure without requiring mating forming dies.
By initially extruding a flat sheet, it is also possible between the extruder and the forming bed to laminate a printed overlay film (such as a wood grain pattern of printing) of material onto the extruded sheet prior to the subsequent forming operation.